There's still much that's unclear about Tuesday's revelation that a small group of hackers in Russia have amassed a database of 1.2 billion stolen user IDs and passwords. The company that disclosed the incident, Hold Security, didn't offer any fresh information Wednesday, but here are five questions we'd like to see answered (and a bonus one that we already know the answer to).

Where did the credentials come from?

Hold Security said the hacking group started out buying stolen credentials on the black market, then used those credentials to launch other attacks. But it's unclear how many credentials they bought and how many of the 1.2 billion they culled themselves. Without that information, it's hard to know how fresh -- and hence how valuable -- the stolen data is.

What websites are they for?

If the hackers managed to recently penetrate major websites, like financial or email services, then it's time to change your password. But if the data comes from mainly smaller sites, the value of the credentials is likely lower -- unless people reused the same password they use for sensitive accounts. You do have unique passwords for important accounts, don't you?

What are the hackers going to do with them?

The answer to this depends partly on the previous two questions. If they are fresh credentials for important services like online banking, they are ripe to be used to siphon money from online accounts. If they are older or from little-used services, they might be used to send spam by email or post it in online forums.

Were the passwords hashed, and how?

Even most small websites don't store passwords as plain text these days, but the scrambling system used to protect passwords called "hashing" offers varying degrees of protection. An older one called "MD5" can be attacked with brute force and broken in a few minutes -- faster if the password is something common like "password123" -- but a more modern and secure method takes longer to break and so is more costly.

Was I affected?

This is the big question for every Internet user. Hold Security says you can sign up for a forthcoming service that will notify you if your details were included. Website operators are being offered a US$120-a-year service that will notify them if their user accounts appear in this or other hacker databases.

Passwords aren't that secure, are they?

Nope, especially as most people implement them today. That's why major websites including Gmail, Facebook and Twitter offer two-factor authentication that requires a password and an ever-changing code produced by a smartphone app, or offer to send a login token via SMS when users connect from a new computer. Security companies are working on new methods for authentication, but it's an ever-continuing cat-and-mouse game with hackers.